Three million people present to emergency departments in the United States each year with symptoms that could represent stroke, and one-half million are ultimately diagnosed with stroke. With the advent of effective therapies, the early and accurate diagnosis of stroke is now of paramount importance. Remarkably, the early diagnosis of stroke often relies entirely on clinical history and physical exam. The development of a serum test for stroke could radically alter the diagnosis and treatment of stroke in the acute setting, and may significantly impact the prognosis of stroke victims. In stroke, ischemia leads to brain tissue damage and disruption of the blood-brain barrier, and a consequent leakage of brain proteins into the bloodstream. We have selected candidate serum marker proteins based on physical properties including brain-specific expression and high abundance in native brain tissue. We have obtained approval from the Committee on Human Research to collect serum samples from patients with stroke and controls. We will perform western blotting and ELISA analyses on these serum samples with antisera to candidate stroke markers to determine their sensitivity, specificity, and time course of elevation in the serum. Our goal is to develop and commercialize a clinically useful serum stroke test. PROPOSED COMMERCIAL APPLICATION Through these studies, we hope to develop an effective serum stroke test that would ultimately be marketed commercially. Such a test would be useful in a wide variety of clinical situations. An effective serum stroke test would be especially valuable in evaluating patients presenting to the emergency department with non-specific neurologic symptoms as well as in monitoring patients undergoing vascular surgical procedures for evidence of neurologic insult.